Titanium base alloys containing tin



Feb. 16, 1954 w. L. FINLAY ETAL TITANIUM BASE ALLOYS CONTAINING TIN 2 Sheets-Sheet 1 Filed March 11, 1955 2 2 l .03 Kfiow QEM Tm, PER CENT EFFECT or" ATMOSPHERE on THE SCALING Aw:

IN V EN TORS.

OF 77 mvo 77-511 ALLoYJ AFTER 41/00::-

AT I050 'C.

ATTORNEYS.

Feb. 16, 1954 w. L. FINLAY ETAL TITANIUM BASE ALLOYS CONTAINING TIN 2 Sheets-Sheet 2 Filed March 11, 1953 vhN dbg

0 WWW QK OON 00 000 com cow cow cow cc cow on. 00. Q! 08. 00- 0Q 8 0? On 0 O O V O O I IN MLTER L.

ROBERT ZJAFFEE. y Hon/ac: E. OGDEN.

A TTORNEXZ Patented Feb. 16, 1954 UNITED STATES PATENT OFFICE *TI'I'ANIUMBASEZlflitfiitCONTAlNING TIN Walter L. Finlay, Beaver, Pa., and Robert L: J afiee,

'Worthington,

and Horace RJOgden, Columbus,

'Ohio, assignors, by directland mesne assignments, to RemCru Titanium, Inc.,

Midland,

' Pa., a corporation of Pennsylvania Application March 11, 1953,:Serial No. 341,796

6 Claims.

This invention pertains to titanium base alloys, and more particularly to strong, ductile and contamination resistant. alloys of titanium'and tin, which may optionally"andbeneficially contain relatively large and controlled amounts of one or more of the interstitials' carbon,-oxygen and nitrogen for further strengthening the same,

while retaining therelmadequate ductilityfor V fabricationpurposes, such" as forgingor rolling or otherwise plastically deforming.

This application is acontinuation-impart. of our copending application Serial No. 222,938, filed "itpril 25,i1951,now forfeited.

lThe strong and ductile titanium-tin alloys of the invention :contain, according to the broad range of analysis, about 1 to 23% tin, although for tin contents below about 5% and particularly 'below about 2.5%, they:requiresubstantial ad- ;ditions oftone or moreof the interstitials carbon, oxygen and nitrogen orcther alloying elements for materially: enhancing the tensile properties as compared to the unalloyed and substantially uncontaminated titanium base metal.

The presence of tin alloyed with the". titanium base metal greatly enhances the tolerance with respect to the interstitials carbon, oxygen and nitrogen without undue embrittlement and with resultant marked strengthening of the alloy. The carbon may range as high as about 1%, oxygen up to.about 0.5 and nitrogen up to about 0.3%.

For imparting a high degree of contamination resistance, i. e. resistance against diffusion into the alloy of atmospheric gases, particularly oxygen and nitrogen, at elevated temperatures up to about 1l00"C., the alloy should. contain upwards of about 5% tinpalthough lesser-amountsdown to"about2% tin-.arematerially beneficial in'this respect. 'Tinvalloyed with titanium base metal appears to be 2 unique in imparting this contamination resistance, and its effect is quite critical with respect to? the degreeof contamination resistance". impartedwcommencing at adminimum ofaboutifi tin.

1 The-alloys or the invention al'ealso characterlzed by) free scaling properties resulting from exposure L to elevated temperatures up to :about 110W 6. under-atmospheric, oxidizing or' alternativelyoxidizing andreducing conditions. That is to say the scale formed-is easily" brushed ofi'or 25id'iificult to achieve.

undergoing no appreciable loss of ductility in the "welded as compared to the non-welded portions.

Substantially pure titanium may be produced at considerable expense by the Van Arkel or iodide process described in Patent 1,671,213. Other methods of production, such as the mag- "nesium reduction of titanium tetrachloride, as described in the Patent 2,205,854 to Kroll, result in ametal of commercial purity containing traces of other metals, such as iron, and quantities of the interstitial constituents, carbon, nitrogen and/or oxygen, which in the range upwardly from'i0101% may be significant. These contaminants have the effect of strengthening the metal but they tend to cause embrittlement. A combination of acceptable strength and ductility is Further strengthening has hitherto been secured by the addition of varying quantities of a variety of other metals, but in general it has been found necessary to use as a base for such alloys, a titanium metal in which the total contaminant content was quite low.

The effect of the three contaminants is substantially additive. Nitrogen is the most potent hardener and strengthener, but ordinarily causes the greatest embrittlement. The strengthening effect of oxygen is usually less than that of nitrogen, while soluble carbon is desirable, but

an'yexcess tends to form embrittling carbides.

The present invention comprises, in one of its aspects, the discovery of a group of binary alloys of titanium and tin which have desirable properties,.and the further discovery that such alloys "will not only tolerate carbon, oxygen and/or nitrogen, in quantitie heretofore wholly unusable but that the presence of one or more of these inaterials results in greatly augmented strength at a high level of ductility. It has: likewise been found that alloys of this group are not susceptible to dee and damaging penetration by atmospheric gases at fabricating temperatures.

Tinis soluble in alpha titanium to the extent otat least 15%, and alloys of titanium with up to 15% tin are all in the alpha phase. As the tin content is increased the beta transformation temperature rises, and at a temperature of about 930 C., and a tin content of about 19% a peritectoid reaction occurs. In alloys containing 20% to 23% tin, two intermediate phases have been tentatively identified.

An alloy containing about tin, balance high purity or iodide titanium, as rolled and annealed for 2 hours at 850 C., has an ultimate strength of 64,000 p. s. i., an elongation in 1" of 18%, and a bend ductility of about 2.8 'I. Increasing the proportion of tin substantially increases strength with only a relatively minor effeet on ductility. As the tin content is increased,

4 of 2.5 T. It will be seen that, as compared with the 5% tin alloy, strength has nearly doubled, while ductility, instead of decreasing in proportion to the increase in strength, is actually slightly improved. A further increase in tin content results in further strengthening with only a minor reduction in elongation and an apparent further improvement in bend ductility. An alloy containing tin, balance substantially pure titanium, after 24 hours anneal at 850 C., has an ultimate strength of 122,000 p. s. i., an elongation in 1" of 12%, and a bend ductility of 1.5 T. The fully annealed alloy containing 22.5% tin shows an ultimate strength of 149,000 p. s. i., elongation in l of 11%, and a bend ductility of 4.7 T. Bend ductility has diminished, but is still acceptable for most uses.

The foregoing and other properties of typical binary titanium-tin alloys, as fully annealed at 850 C., are tabulated in the following Tables I and II for iodide base titanium metal and that of commercial purity, respectively.

TABLE I Tl-Sn binary alloys (iodide titanium base) annealed condition Tensile Properties: p. s. i.X1,000 P (lomrtioagtiim,

ercen a ance 0.2% Ultimate Percent Percent Mm. Tltamum) Sn Ofiset Tensile Elongation Reduction Bend 5532 Yield Strength in 1 in Area T l Annealed 1 hr. at 800 C. 7 Annealed 2 hrs. at 850 C. Annealed 1 hr. at 850 C. 4 Annealed 24 hrs. at 850 0.

TABLE II Ti-Sn binary alloys (commercial purity titanium base) annealed condition Tensile Properties: 1). s. i.X1,000

Composition, Percent (Balance 0.27 Percent Percent Mm Titamum), Sn ofisgt Ultimate E1011 Vickers gation Reduction Bend Yield Strength in in Area Hardness T 1 Annealed at 950 0.; other analyses annealed at 850 C. 1

The alloys of this invention are characterized taminants, oxygen, nitrogen and carbon. .The addition of one or more of these interstitial components in amounts substantially greater than those usable in other titanium alloys has a pronounced strengthening efiect with a relatively small loss of ductility. Moreoventhetolerance for oxygen and nitrogen remains substantially 6 exampla'zalloystof titanium with up to at least 15% tin, .mayzoontain as .much as 0.3% nitrogen andstiilpossess :aiductilityadequate for the most exactingrotxall zuses, viz. sheet which is stretched in fabricating to finished form. The efiects of controlled and, progressively increasing "additions of these interstitials to the binary alloys ofTables I and II..are shown in the following Tables III the same over a broad range of tin'content. 1 For $10 and IV; respectively.

-.'I'ABLE III :L'Ii-Sh alloys containing interstitial additions (iodidatitaniuml base) anneal condition Cmpositionf1ercent .(Balance Titanium) Tensile Properties: p; s. LXLOUO Percent Percent 1 3 Min. 511 0 TO N 02% Ultimate Elongation Reduction vlckers ITBend I set Yield Strength ml in Area Hardness O 27 1 43 '40 61 105 0 1 0. 1 46 x 59 i 34 l 52 189 0.5

1 0:2 55 70 128 s 48 205 0 25 0.1 55 i 66 131 55 220 0.5 2.5 022 65 v74 .720 51 235 0.5 0.1 65 i 74 I 26 Z 57 239 0. 5 6 1 0.2 79 .83 29 53 265 0.5

5 1 0. 4 92 .99 24 51 290 0 5 0.5 109 117 I124 4a 325 1.3 5 0:75 119 130 10 14 380 5.8 5 1 .123 138 '7 13 387 .8.6 T 10 1 0.1 79 '88 I 21 i 57 282 1.0 10 0.2 97 102 24 60 308 1.0 1o 0. 4 124 124 .14 49 359 0.0 10 1 0:5 130 147 .17 151 373 2.1

10 0.75 164 0 0 433 0.1 93 104 L14 .49 302 1.4 .15 1 0.2 122 127 "11 '32 304 1.6 .15 1 0.4 .155 162 .4 334 423 13.6 1 .0. 1 49 67 F 28 45 208 .1. 5 1 0.2 64 s4 .38 247 2.0 2. 5 :0. 1 57 I 74 5 26 41 235 1.4 2'. 5 r 0; 2 71 .90 '24 '1 33 274 2. 0 6 0.1 61 78 23 1 49 268 1.4 5 0. 2 79 96 23 47 312 1. 0 *5 0.3 102 113 21 46 305 2.1 5 0. 4 108 122 12 15 380 6. 1 5 0. 5 128 128 1 10 423 7. 6 1 -10 .0.1 81 .94 .22 44 319 1.5 1O 0.2 99 112 16 32 360 1.7 i :10 11 0.3 116 1.127 "4 303 21 .10 0.4 131 v138 1 23 410 0.5 15 0L1 105 I17 14 46 304 2. I .515 00.2 96 I L112 "20 :325 1.1 .7 15 03 124 1 .134 2o .40 .380 I213 5 0J5 147 155 11 "38 300 *3'. 2 .1 10.11 1 E83 .20 .40 225 2.0 1 1.012 94 .105 14 33 310 I20 7 2.5 0. 11 20 -35 258 2.3 2:5 032; L .109 :16 26 332 rI:7 5 0.06 1 62 81 23 .30 233 '2.0 '5

"0.11 so 97 -19 29 1296 l :20 1 15 0:21 107 .115 11s 23 366 2.0 .15 .029 1 20 .123 120 .47 348 213 "10 1 0106 64 ""78 1'18 "50 262 P222 1 10 0.11 88 100 .18 .32 '297 .21 10 0.18 120 124 13 .38 F 358 1.5 10 0.27 128 134 "18 46 f 354 2.2 15 0:08 81 .189 16 46 310 .2: 3 15 0..13 111 118 167 44 343 1'. 7 l5 -0.2 131 137 14 "36 391 :22 15 0. 20 144 151 we 25 387 2.1 15 0.3 146 .1154 12 38 397 -i 2:9

' Brittle.

TABLE IV Ti-Sn allloys containing interstitial elements (commerical purity titanium base) annealed condition gggg g gg ifi fig Tensile Properties: p. s. i. 1,000

- Percent Percent Min. 0.27 Ofi- Ultlmate Vickers Sn O N set l field Strength fi g ggg Hardness gt From these results it will be observed that adcrease in tensile strength as compared to the unditions of tin up to about 23% greatly strengthen alloyed titanium base metal, the further addition the metal while'retaining adequate ductility for of 0.1 or 0.2% of carbon, oxygen or nitrogen infabrication purposes, i. e., forging, rolling, etc. (in creases the ultimate strength by 30% to For the iodide titanium base the yield strength without noticeable effect in the ductility as comis more than quadrupled from 27,000 to 135,000. pared to the unalloyed titanium base metal. p. s. i., while the ultimate strength is more than Further increase in the interstitial content tripled from 43,000 to 149,000 p. s. i. For any further enhances the strength while retaining given tin content further strengthening results 05 adequate ductility. In this way the tensile from controlled additions of one or more of the strength of the material may be raised to as interstitials. Thus, at the 5% tin level, the admuch as about 160,000 p. s. i. with retention of dition of 0.5% carbon, approximately doubles the adequate ductility as shown, for example, by the yield and ultimate strength without reducing 19% tin, 0.2% carbon, commercial purity base ductility. 'Oxygen and nitrogen additions have 70 analysis. generally similar effects as shown. The effect The alloys of this invention show an unusual of the interstitials in strengthening the titaniumbehavior with respect to scaling and contaminatin alloys in the low tin range of under 2.5% tin tion resistance at forging and rolling temperais particularly to be emphasized. Thus wheretures, say temperatures between 900 and 1100 as the Ti-l% Sn binary shows little or no in- 75 C. Titanium itself and most alloys thereof are subject to deeprpenetration by, atmospheric-gases atlthesetemperatures. For example, when substantially; pure titanium exposed. to atemperature-of 1000- C. for 2ihours its Knoop hardnessll number at a depthof 0.012" beneath the surface is increased from about 100 tow nearly 300. For alloys of titanium with 5%,n10%-0r TABLE-V I 15% tin, the change in hardness at the surface 1 and at zany distance: below the surface up to at ggiga least ,0l0121, after" a' similar high temperature o pqs t n; fe w cB -Ti exposurepis negligible: At such temperatures, (mmmmalpumy) 1 the tin alloys form a surface scale which flakes Welded Welliesoiflmleavingm fresh". surface :of essentially the 1 original surface composition. and: hardness. 1.5: 0. 8 Troublesome and wasteful clean-up after fqrgingiis thus obviated. At service temperatures 0,? 1 2 as high as'about 425 -C., alloyscontainingiupto i; 1 {i tin are practically immune to'surface oxida- I 1.3 tion, being in this. respect 1 comparable with 7 12 titanium itself. 20 {'3 In the annexed drawings: 21. 2L7 Figs. 1a and 1b illustrate graphically the seal- 1 ingeffectsafter fourv hours at 1050C. in air, 113mm TABLEVI Tensile Properties: p. s. l.Xl,000

Composition, percent, Welded Not Welded Bal. Ti (Commercial purity) Percent Percent Percent Percent g gg'gif Eloirl lgation Rfglgriteign g gggf Eloinlglation Rieliigcglgn 2Sn-0.l3C 92 19 100 29 52 rsn-mao 91 19 29 102 21 52 751141.130 101 11 25 114 23 so 9,5Sn0.l 115 11 27 13s is 42 lOSn-OJOC. 111 10 22 132 16 42 nitrogen and oxygen respectively, in terms of metal loss and weight gain respectively, as ordinates, versus tin content, as abscissae, for the binary alloys of the invention.

Figs. 211-0 show graphically the scaling properties and contamination resistance under the conditions above specified of titanium metal of commercial purity; while Figs. 3a-c, 4ac and 5a-c present corresponding data for the binary Ti-Sn alloys of the present invention for tin contents of '5, 10 and 15%, respectively.

Referring to Figs. 1a and b, it will be observed that the elevated temperature scaling in a nitrogen atmosphere (N2) increases slowly and then more rapidly with increasing tin to a maximum at about 7% tin and drops off thence quite rapidly for higher tin contents. In an oxygen atmosphere (02) the scaling decreases progressively with increasing tin from a maximum at 0% tin. The curve for scaling in air is substantial a composite of the nitrogen and oxygen graphs, decreasing from a fairly high value at 0% tin to a minimum at about 2.5% tin, rising sharply at upwards of about 5% tin to a maximum at about 7% tin and dropping 01f rapidly thereafter. As stated the scale formed scales off freely and easily leaving a clean metal surface, this being particularly so in the range of 8 to 16% tin and specifically 10 to 15% tin.

Referring now to Figs. 2a to 50 inc., it will be seen that whereas the unalloyed titanium base metal is subject to deep penetration and accom panying surface hardening by oxygen, nitrogen and atmospheric gases at elevated temperatures, the opposite is true of alloys according to the invention containing upwards of 5% tin.

The upper limit for the interstitials for ductile Welds are about 0.3% oxygen, about 0.2% nitro en and about 0.3 carbon.

The alloys may be made by melt casting in a cold mold, employing an electric arc in an inert atmosphere, or may be produced in other ways in which the alloy is rendered molten before casting.

As shown by the data in Tables I-IV inc. the alloys of the invention in general possess ultimate strengths at least 10% in excess of that of the unalloyed titanium base metal, with tensile elongations in general upwards of about 10% and minimum bend ductilities under 9. The vast majority of the alloys of the invention possess ultimate strengths at least 30% to 50% in excess of that of the unalloyed titanium base metal, and this includes the low tin analyses containing one or more of the interstitials in substantial amounts. Where the alloys are to be used in the form of sheets their bend ductilities may range as high as 20 T, and where used in massive form, as in forgings, the tensile elongations may range as low as 1 or 2%. Bend ductility is the minimum radius to which the specimen can be bent through an angle of 75 without fracture, expressed as a multiple of the thickness.

What is claimed is:

1. A ductile titanium base alloy containing: about 5 to 23% tin, up to about 1% carbon, up to about 0.5% oxygen, and up to about 0.3% nitrogen, characterized in having an ultimate strength at least 10% in excess of the unalloyed titanium base metal. 2. A ductile alloy consisting of: about 5 to 2; tin, up to about 1% carbon, up to about 0],

ance titanium.

3. A ductile titanium base alloy containing: about 5 to 19% tin, up to about 1% carbon, up to about 0.5% oxygen, and up to about 0.3% nitrogen, characterized in having an ultimate strength at least 10% in excess of the unalloyed titanium base metal.

4;. A ductile alloy consisting of: about 5 to 19% tin, up to about 1% carbon, upto about 0.5%

oxygen, up to about 0.3% nitrogen, and the balance titanium.

5;An alloy consisting essentially of about: 1

6; An alloy consisting essentially of about: 2.5 to 23% tin, at least one element selected from I thegroupconsisting ofcarbon, oxygen and nitrogen inminimumamount-of 0.1%. and in maxi-' mum amount of 1% for carbon, 0.5% for oxygen, and 0.3% fornitrogen, balance titanium, characterized in having in the annealed condition an ultimate strength at least 30% in excess of the unalloyed titanium base metal, and a minimum bend ductility under 20 T.

WALTER L. FINLAY. f

ROBERT I. JAFFEE. HORACE R. OGDEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,020,515 Rossi Mar. 19, 1912 1,022,598 Rossi Apr. 9, 1912 OTHER REFERENCES Journal of Metals, March 195.0,:page 498. Research and Development on Titanium. Al-

loy s (part, 2) published June 1950 as: AF Tech- 

1. A DUCTILE TITANIUM BASE ALLOY CONTAINING ABOUT 5 TO 23% TIN, UP TO ABOUT 1% CARBON, UP. TO ABOUT 0.5% OXYGEN. AND UP TO ABOUT 0.3% CHARACTERIZED IN HAVING AN ULTIMATE STRENGTH AT LEAST 10% IN EXCESS OF THE UNALLOYED TITANIUM BASE METAL.
 5. AN ALLOY CONSISTING ESSENTIALLY OF ABOUT: 1 TO 23% TIN, AT LEAST ONE ELEMENT SELECTED FROM THE GROUP CONSISTING OF CARBON, OXYGEN AND NITROGEN IN MINIMUM AMOUNT OF 0.1% AND IN MAXIMUM AMOUNT OF 1% CARBON, 0.5% FOR OXYGEN, AND 0.3% FOR NITROGEN,BALANCE TITANIUM, CHARACTERIZED IN HAVING IN THE ANNEALED CONDITION AN ULTIMATE STRENGTH AT LEAST 30% IN EXCESS OF THE UNALLOYED TITANIUM BASE METAL, AND A MINIMUM BEND DUCTILITY UNDER 20T. 